Automatic circuit interrupter



April 17, 1962 K. H. DATE ETAL' 3,030,476

AUTOMATIC CIRCUIT INTERRUPTER Original Filed Feb. 14, 1957 '7Sheets-Sheet l April 17, 1962 K. H. DATE ET AL 3,030,476

AUTOMATIC CIRCUIT INTERRUPTER original Filed Feb. V14, 1957 7sheets-sheet INVENTORS. Kazuo Henry Date Anthony Van @yan www April 17,1962 K. H. DATE ETAL 3,030,476

AUTOMATIC CIRCUIT INTERRUPTER Original Filed Feb. 14, 1957 l 7Sheets-Sheet 3 IN VEN TORS.

Kazuo Henr .Date

Anthony an @yan 4 tto rfrey' K. H. DATE ET AL 3,030,476

AUTOMATIC CIRCUIT INTERRUPTER '7 Sheets-Sheet 4 i f. w mum, W l ma w WVn/ ww a www y@ MW, M will J ,dw KAN w 7 w f C April 17, 1962 OriginalFiled Feb. 14, 1957 174 Wsw April 17, 1962 K. H. DATE ET AL 3,030,476

AUTOMATIC CIRCUIT INTERRUPTER 'original Filed Feb. 14, 1957 '7Sheets-Sheet 5 IN VEN TORS. Kazuo Henry .Date BY n/lorzy I/Zrz /fyan @CwMM April 17, 1962 K. H, DATE ET A1.

AUTOMATIC CIRCUIT INTERRUPTER Originali, Filed Feb. 14, 195'? MQ .D Nmlc.. wy e mem m .t TMV. 0 n MDR a .w w m A W IWV/ e e0! m Hm w M Z @MApril 17, 1962. K. H. DATE ETAL 3,030,476

AUTOMATIC CIRCUIT INTERRUPTER Original Filed Feb. 14, 1957 7Sheets-Sheet 7 INVENTORS. Kazuo Herv Date qnt/zon] l/an Ryan.

United States Patent O 1 Claim. (Cl. 20G-e150) This invention relates toimprovements in an automatic circuit interrupter of the type commonlyknown as ya dual time-current characteristic recloser.

Reclosers are generally installed in electrical distribution systemsadjacent each other in a main line or at the origin of a branch linewhich in 4turn supplies other subsidiary lines that are protected byfuses. lIn the event that a fault occurs on the line ahead of it, therecloser is usually adjusted to execute a sequence of at least two fastopening operations and somewhat delayed reclosing operations duringwhich time most faults will clear without melting the fuse. Therelationship of the fault current to the time required for opening theinterrupter during the fast opening operations is such that the recloseris faster than'the melting time-current characteristic of the fuse sothe recloser itself is relied upon as a sole means for attempting toclear the fault without damage to the fuse.

`rIn instances where the fault is not cleared during a fast openingsequence the recloser automatically changes its time-currentcharacteristic so that further opening operations are retarded to theextent that there is sufficient time to melt the fuse provided thelfault current is of great enough magnitude. If the fault clears kdue tomelting the fuse or for other reasons during any of the successiveoperations, the recloser closes and maintains power on the line. If thefault does not clear during the total sequence of fast and retardedopening operations, the recloser automatically locks out and disconnectsthe branch line being protected from its source. 'ln order to properlycoordinate a particular recloser with other reclosers and fuses it isimperative that the recloser have a predictable tirnecurrentcharacteristic throughout its entire expected fault current range. Also,the number of instantaneous opening operations, the number of retardedoperations, and the total number of operations to effect lockout must beunder convenient control of the customer at the time of installation.

Although prior art reclosing circuit interrupters have been used withconsiderable success, they have not always demonstrated optimumprecision and uniformity insotar as tixne-current characteristics areconcerned because of erratic behavior resulting from variations inmanufacturing tolerances and unpredictable dynamics over a widelyvarying range of currents between minimum trip current setting andmaximum fault current interrupting rating.

Another problem is that of enabling the customer to conveniently .Selectthe total number f Operations which the recloser is to execute beforelozlgingV out and to select the number of fast operations beforeretarded operations are put into effect.

Another problem in prior art reclosers is assuring that fault currentinterruption is initiated at a definite time during each operation`following occurrence of a fault and that interruption is completed withutmost .rapidity but without bounce or recoil of the moving partsforming the interrupting switch means to the end that propercoordination will not be defeated by sustaining the interruption processfor any but the most yabbreviated interval.

An Vobject of the present invention is to provide a re- 3,030,476Patented Apr. 117, 1,962

ICC o 2 closing circuit interrupter that utilizes a portion of theenergy obtainable from a series electromagnet conducting. fault currentfor the purpose of establishing a precise commencement and terminationof a time delay period which is followed by a quick opening of theinterruptor switch means. i'

Another object of this invention is the provision of a circuitinterruptor that responds to occurrence of a fault by firs-t applyingsubstantially all of the fault current energy to a magnetic plunger forcarrying out a timing interval that begins and ends before interruptioncornmences and then by applying substantially all of the fault currentenergy -to opening the switch means.

A further object, to be considered in conjunction with the aforegoingobjects, is the provision of a hydraulic timing mechanism that includesan integrating piston adapted to advance in a step-by-step manner, bymeans of uid displaced from a hydraulic pump, toward a lockout meansactuating position and towardy a position where the integrating pistonautomatically converts the fast interrupter switch openings to retardedopenings by blocking 'a fluid escape orifice and wherein the hydraulicrneeha'- nisrn is novel in the respect that it is ineffective to allowoperation of the switch opening mechanism until after the opening timedelay interval has been completed. An important corollary of this objectbeing that the escape orifice ycannot be partially blocked by theintegrating piston so as to alter the timing characteristic of the'interrupter while itis executing a particular opening operation, butrather, that the integrating piston will only advance after timing ofthat operation is completed.

Another object of the present invention is to initiate opening of theinterrupting switch means by sharply irnpacting the movable contactmeans by the" magnetic plunger at the exact moment in which thetime'delay ,function of the plunger is completed and at which time theplunger is substantially unimpeded andv is traveling at maximumvelocity. i Y I Y A further object of the present invention is toprovide in a dual time-current characteristic recloser adjustable meansfor conveniently selecting the total number of opening and reclosingoperations prior to lockout and for selecting in any operationalsequence, the numberV of fast and retarded switch openings. An adjunctto this `object being that the operating characteristic of theinterrupter is subject to the discretion of the customer `so that therecloser may be readily coordinated with otherslike it and with fuses inthe same distribution system.A I I A further object of this invention isto incorporate an improved interrupting switch means that is capable ofclearing fault currents with great rapidity Iand which interruptingswitch is simple in form, economical to manu,- tfacture and easy tomaintain or replaceQv l A Another important object is to provide aninterrupting ,switch means having movable ,components-that are sud denlyarrested in their motion by a highly simpliied means for preventingcontact rebound with a viewto# ward obviating arc restrikes and therebyimproving reliability and coordination withfuses.

It is a general .object of the invention to provide a new and improvedautomatic reclosing circuit interrupter that has precise time-currentcharacteristics and a higher and more eiicient current interruptingcapacity for an equivalent size than those heretofore known. vOtherVmore speciuc objects may be observed periodically throughout the courseof the ensuing speciiication. l u i The novel interrupter will tirst bedescribed in general terms and then in detail in connection withthefollowing drawings in which: y`

FIG. l is a vertical sectional elevational view, with parts broken away,of a reclosing circuit interrupt'er assembly embodying the invention;

FIG. 2 is a top plan view, partly in section, taken on the line 2-2 ofFIG. 1 showing components constituting the timing and integratingelements of the interrupter;

FIG. 3 is a vertical elevational sectional view taken on the irregularbroken line 3-3 in FIG. 2;

FIG. 4 is a vertical sectional view of parts of the interruptercorresponding with closed circuit position of the interrupting switchmeans;

FIG. 5 is a view similar to FIG. 4 but showing the same parts as theyappear at the end of a time delay interval following occurrence of afault on a power system;

FIG. 6 is similar to the two preceding figures but shows the parts ofthe interrupter as they appear when the interrupting switch means is inopen position;

FIG. 7 is a portion of the interrupter timing and integrating mechanismtaken from the left side when viewed in respect to FIG. 1;

FIG. 8 is a sectional view showing a portion of the mechanism similar tothat shown in FIG. 3 but with thejintegrating piston in an initiallyadvanced position; FIG. 9 is a sectional view taken on the line 9 9 ofFIG. 7, with parts broken away;

FIG. 10 is an elevational view of the interrupter switch means taken`from the left side with respect to IFIG. 1;

FIG. 1l is a sectional view taken on the line 11--11 in FIG. l showingcomponents of the interrupter switch means as they appear when in normalor closed circuit condition;

FIG. 12 shows the same components as in FIG. 11 as they appear at thecompletion of the time delay period following occurrence of a fault;

FIG. 13 is similar to the two preceding figures except that thecomponents are shown as they appear when the v4interrupter switch meansis in full open position; and,

FIG. 14 is a plan view, partly in section and with `parts broken away,of the arc extinguishing structure of the interrupter switch means.

Before proceeding with a detailed description of the invention, anoutline of the general construction and mode of operation of the novelcircuit interrupter will be set forth primarily in reference to FIG. 1.Referring lto that ligure, it will be seen that the interruptercomprises a metal tank 1 filled with dielectric fluid such as oil to thelevel indicated by the dashed line 2 and provided With a gasketed cover3 and an insulating liner 4. Tank 1 is adapted to be mounted on atransmission pole by means of brackets which may be afxed to the tank byany suitable meansl such as welding. Cover 3 is provided with a pair ofbushings 6, one of which is shown, for the purpose of seriallyconnecting the recloser in a power line. The current path through therecloser between the two bushings yconstitutes a series circuitincluding an electromagnetic trip coil 7 and interrupting switch meansgenerally designated by numeral 8. The lead wires extending through thebushings and connecting the electromagnet coil 7 and switch means 8 inseries are omitted for the sake of clarity. A magnetic plunger 11 isadapted to be drawn downwardly into VVcoil'7 when a minimum trip currentis reached upon which event the interrupting switch means 8 is openedand series coil 7 is de-energized. Means, to be discussed later, areprovided for returning plunger 11 to its uppermost position followingeach successive switch opening and de-energization of the series coil 7.

Each time plunger 11 descends it causes a pump piston 12 to deliver ameasured quantity of oil under an integrating piston 13, see FIG. 3,which elevat'es step-bystep in a cylinder 14 and accordingly causessimilar advancement of a trip stem extension 15. After a predeterminednumber of such operations, usually four, trip stem extension 15 advancesto where it strikes a latch finger 25 controlling a spring-biasedtoggle-link lockout mechanism 26. Collapse of the toggle-link mechanismcauses plunger 11 to descend and hold the interrupter switch means 8open permanently or until the toggle mechanism is reset manually.

The first in a series of such opening operations are usually quicklycompleted following the occurrence of a fault and those operationsfollowing in close succession are retarded automatically in order togive the interrupter a dual time-current characteristic. This matterwill be discussed in greater detail hereinafter.

The general features of the interrupter thus far outlined are wellestablished in the art and for those who are interested furtherdiscussion of them may be found in Patent No. 2,560,831, issued to A.Van Ryan et al. July 17, 1951, and No. 2,710,895, issued to R. S.Frederickson June 14, 1955, both of which are assigned to thepredecessor of the instant assignee.

Attention is now turned to a more detailed description of the novelrecloser. Its operating mechanism is suspended from cover 3 by means ofinsulating stringers 27, two of which are. shown in FIG. 1, so that theentire mechanism in tank 1 may be removed with cover 3. The faultresponsive element is the series electromagnet coil 7 which isinterposed between a lower magnetic plate member 28 and an uppermagnetic member 29 constituting the timing mechanism casting. The twomagnetic members 28 and 29 are tied together by a pair 0f vertical metalposts 30 for the purpose of completing a magnetic circuit about coil 7.

The series coil 7 is rated according to its normal ful load current andit is adapted to attract magnetic plunger 11 downwardly when the currentto the coil exceeds twice normal current, this being known as theminimum trip current of the interrupter. Coil 7 is wound on a flangedinsulating spool 32 provided with a central bore 33 constituting thecylinder in which the magnetic plunger 11 reciprocates during openingand closing operations. The lower endrot spool 32 is gasketed at 34 andbears near its short radius central portion on the shoulders of a guideplug 35 fastened by any suitable means such as a press fit in the bottomplate 28 of the magnetic circuit about the coil 7. t

Between the upper face of flanged spool 32 `and the hydraulic timingmechanism casting 29 there is inter- 'is displaced and dischargedthrough orifice 3S into slide valve cylinder 39.

At the top of cylinder 39 there is a slide valve 40 normally biasedagainst a shoulder 41 by means of a cornpression spring 42. SlideV valve40 is provided with a small orifice 43 that is closed by a disc valve 44under the influence of hydraulic pressure developed in slide valvecylinder 39 when plunger 11 moves downwardly.

DuringV opening operations of the recloser, fluid pressure developed bythe descent of plunger 11 causes disc valve 44 toclose orice 43 andslide valve 40 to be elevated in opposition to `compression spring 42.Under these circumstances,slide valve 40 opens an escape orifice 45which leads from slide valve cylinder 39 to the integrating pistoncylinder 14. The last mentioned cylinder is open at its top so that uidrejected from escape orifice 45 is free to discharge into the body ofdielectric fluid stored in tank 1. During fast opening operations of theinterrupter, fluid displaced by plunger 11 escapes so rapidly throughthe escape orice 45 that there is very little impedance of the plungerdescent. Retarded or time delay openings are brought about whenintegrating piston 13 advances to close escape orifice 45.

It will be explained shortly hereinafter that plunger 11 operates aninterrupter switch assembly 8 each time the plunger descends. VThe sameassembly includes over cen- Y tervspring means for returning the plungerupwardly tcv its normal position as viewed in FIG. 3 as soon as theinterrupter switch opens and magnet coil 7 is de-energized. During thereturn stroke or ascent of plunger 11, slide valve 40 drops downwardlyand stops on shoulder 41 to close escape orifice 45 and the only fluidthat can be drawn into plunger cylinder 33 for permitting plunger 11 torise is that which is throttled through the small orifice 43 around thedisc valve 44 in the slide valve. Thus, reclosing of the interrupter issomewhat time delayed to provide time for a fuse to cool or a fault toclear.

Note that plunger `11 is connected to an L-shaped lever 48 by means ofan insulating link 49. Lever 48 is journalled loosely on a main shaft 50to which an external manual operating handle, not shown, is fastened(see the above cited Frederickson patent). An arm 51 of lever 48 whichsupports the plunger link 49 also has pivotally connected to it at ashorter radius with respect to shaft 50 another insulating link 52 whichactuates a pump piston assembly 12. Each time plunger 11 descends,piston 12 also descends and forces denite quantity of fluid from thepump cylinder 53 through semicircular duct 54 milled in thebottom ofcasting 29 for placing the integrating piston cylinder 14 and pumpcylinder 53 in communication. The bottom of duct 54 is closed by agasket 60 compressed against ring 36. Pump piston 12 is effective todisplace fluid only on a downward stroke by reason of it being providedwith a ball check assembly including a ball 55 and a spring 56, see FIG.3. When the downward stroke of pump piston 12 is initiated, fluid isfreely discharged through a relief aperture 57 through the wall ofcylinder 53. Piston 12 becomes effective to displace fluid into theintegrating piston cylinder 14 upon fully closing the relief aperture57. This cut-off point may be controlled or adjusted by axially movingan internally threaded shell S surrounding the piston body 59. Byreference to FIG. 5 it will be noted that the eifective point in thepump piston stroke begins when arm 51 of L-shaped lever 48 issubstantially in a horizontal position. This means that the verticalcomponent of the arm 51 angular velocity is greatest when pumping isinitiated.

As explained before, each stroke of pump piston 12 delivers a denitequantity of fluid through duct 54 into integrating piston cylinder 14.Integrating piston cylinder 14 has at its bottom a ball check 61 whichpermits easy ingress of fluid to cylinder 14 but prevents discharge backinto the duct 54. During a closely successive series of plunger 11 andpump 12 operations, the measured quantities of fluid urge theintegrating piston assembly 13 upwardly in cylinder 14. If thesuccessive series of interrupter operations do not terminate in lockout,integrating piston 13 will slowly resettlefrom an intermediate positionto its original lowermost position as shown in FIG. 3 under theinfluence of a return spring 62. During step-by-step advancement ofintegrating piston 13, integrating piston 13 advances to a positionwhere it closes escape orice 45 and prevents discharge of fluidtherethrough from slide valve cylinder 39. This produces back pressureand retards operation of plunger 11, and accordingly, time delaysopening of the interrupter following occurrence of a fault. Duringretarded operations of the plunger, slide valve 40 is, of course, urgedupwardly but this has little eifect on relieving pressure in slide valvecylinder 39 because disc valve 44 closes small orifice 43 in the slidevalve body. Thus, the only escape for fluid during retarded operationsis that which occurs as a result of leakage. It will be explained morefully hereinafter how, according to the instant invention, the number offast and retarded operations may be easily selected and how the totalnumber of interruptor operations prior to lockout may be selected.

The relationship of the current traversing coil 7 to the time in whichthe interrupting switch 8 opens, or in other words, the shape of thetime-current characteristic curve of the interrupter may be preselectedfor coordination with the particular fuses applied in a branch circuitby other Well known means. One of these is a multiapertured selectorplate 64, see FIGS. 1, 2, 7 and 9, secured against the wall of the slidevalve cylinder 3.9 by means of a cap screw 65 and positioned by anindexl pin 66. The apertures 67 are of diiferent diameters and arearranged for rotation into registry with a hole 68 that connects withthe slide valve cylinder 39. Thus, when slide valve 40 is urged upwardlyduring either fast or retarded interrupter operations, a certainquantity of iluid displaced by plunger 11 may be discharged through anyselected one of the registered apertures 67 to provide variable timedelay or retardation.

Another means for effecting a quicker plunger 11 response, particularlyduring high magnitude faults, is through the agency of a relief valveassembly 70. The relief valve assembly 70 is now well known in the artand need not be explained in detail except to say that when the pressureinside of slide valve cylinder 39 exceeds a certain value, relief valve70, which may be of the ball check type, is adapted to discharge uidfrom the slide valve cylinder 39 to the ambient oil of the tank. Valve70 acts as a safety relief and tends to make the time-currentcharacteristic curve of the interrupter steeper or faster in the rangeof high magnitude fault current so that the curve more nearly parallelsthat of fuses.

Note that plunger' 11 has attached at its lower end a self-aligningdownwardly extending switch actuating rod 72 which passes through theplug 35 supporting solenoid spool 32, see FIG. ll for example. Switchactuating rod 72 is recessed into the end of plunger 11 and is looselycarried on a transverse pin 73 to relieve the effects of anymisalignment of the plunger. In FIG. ll it will be observed that whenplunger 11 is in its uppermost position, the lower end of rod 72 bearson a roller 74 rotatably carried on a pin 75 at the end of a pivotal arm76 forming part of the interrupter switch assembly 8. This is the closedcircuit position of the interruptor switch assembly 8. On the otherhand, FIG. 13 illustrates that when plunger 11 descends to its lowermostposition the interrupter switch is in full open position. The importanceof the relationships between the components of the interrupter switchassembly 8 and the various components discussed earlier in connectionwith describing the hydraulic timing mechanism will be set forth shortlyhereinafter.

A more detailed examination of plunger 11 and its associated parts willnow be made. Note that the plunger is arranged to slide through a bore80 in the timing mechanism casting `29. The lower extremity of bore 80includes the upper surface 38" of the discharge orifice 38, see FIG. 3.The upper extremity of bore 80 is defined by a shoulder `81 countersunkin the upper surface of casting 29 as shown. Plunger 11 is provided witha plurality of axial surface slots 82 opening at their lower ends 83into cylinder 33 when the plunger is in its uppermost position as inFIG. 3. Slots 82 also normally open above shoulder 81 as seen in FIG. 3and thereby place cylinder 33 and the ambient fluid in communicationwhen the plunger is up. Hence, when plunger 11 begins its descent inresponse to a fault, itis incapable of forcing fluid into the slidevalve cylinder 39 since the fluid Willbe freely discharged through theupper end 83 of axial slots 82. This condition is observable in FIG. 3.As plunger 11 begins its descent, however, the upper end 84 of axial`slots .82 is .closed by passing the shoulder 81 of casting 29. Timingor retardation of plunger 11 stroke then becomes elfective because fluidis then principally relieved :through the restricted escape orice 45.

Note also that the upper Vend of plunger 11 is Irecessed at 85 andprovided with a Vcross pin 86 to which is attached insulating link 49.Recess 85 has radial relief 'through each plate member 90, 91.

ports 88 which, when the plunger is in its uppermost position, isremotely spaced from discharge orifice 38, see FIGS. 3 and 4. In FIG. 5it Will be noted ythat relief port 88 descends during a fault currentimpulse into substantial registry with discharge orifice 38 leading toslide valve cylinder 39. When overlapping of relief port 88 anddischarge orifice 38 occurs, all of the pressure developed in the slidevalve cylinder 39 by descent of plunger 11 is suddenly relieved tocomplete the timing interval. After that it is seen that plunger 11 isable to move from an intermediate position in its stroke as shown byFIG. 5 to a final position shown in FIG. 6, entirely unimpeded since anyfluid displaced by the plunger 11 is freely discharged from the reliefport 88 at this time. It will appear below that the interrupting switch8 is opened by a sharp impact only after the timing interval iscompleted.

The effective plunger stroke, and therefore, the timing interval, isgoverned by precise tolerances in the length of slots 82 and byprecisely locating relief port 8S. The vertical distance between theextremities 81 and 38 of casting 29 are also carefully controlled andsince these dimensions cannot vary during operation and wear of therecloser, its timing remains constant and uniform throughout its life.Hence, the machining tolerances of any of the other lever mechanism thatsupports the plunger or of the interrupting switch structure are ratherimmaterial.

Consider now the relative position of plunger 11 with respect to pumppiston 12, both of which are carried on arm 51 of lever 48. When therelief ports 88 of piston 11 begin to register with discharge orifice 38to permit the plunger to descend unimpeded at the end of the timinginterval as shown in FIG. 5, pump piston y12 ,commences to force fluidinto the integra-ting piston cylinder 14. This is clearly demonstratedin FIG. 5 where relief aperture 57 in the pump cylinder 53 is fullyclosed by the downward stroke of pump piston 12. Therefore, integratingpiston 13 begins to step upwardly towards closing the escape orifice 45only after the timing operation of the interrupter has been completed.This means that the integrating piston 13 cannot partially close escapeorifice 45 and thus vary the shape of the recloser timecurrentcharacteristic curve except between interrupter switch operations whenit is desirable to automatically transfer from an instantaneoustime-current curve to a retarded curve. This is an important aspect ofthe invention since it allays the ill effects of fluid dynamics sufferedwith prior art reclosers.

Before proceeding to show the relationship between the plunger 11 at itsvarious positions and the position of the elements comprising theinterrupter switch assembly 8, the latterwill be described in detail.Referring vto FIGS. l and -14 it will be seen that the interrupterswitch 8 comprises a pair of insulating plates 90 and 91 in spacedrelationship .to each other `and each of which is secured to U-shapedmounting brackets 92 by machine screws for example. In FIG. 10 it isevident that the whole interrupter switch assembly 8 is adapted forconvenient mounting and exchange by securing the brackets 92 to bolts93, projecting through posts 30 and base plate 28, by means of a pairo'f nuts 94. Parallel insulating plates 90, 91 yare preferably made of asemi-compressible material such as phenol formaldehyde resin or the likewith em'beddedreinforcing fibres. The parallel plates 90 and 91 arespaced at their bottom edges by means of a metal cylinder 96. In linewith cylinder 96 on the outside of each of the plates are laterallyextending similarcylindrical members 97, 98, see FIG. 10, which membersconstitute stops for arresting the motion of a pair of movable contactarms without rebound during the process of interruption. Cylinders 96,97, 98 `are held in coaxial compressive relation by a flared rivet 99which passes snugly through the cylinders and Aan appropriate hole It isan important Ahyde resin, for example.

feature of the present invention that the mass, of cylin. drical stopmem-bers 96--98 be carefully selected, since, as will appearhereinafter, the value of their masses has an important function inpreventing rebound of the movable contact arm 100 of the interrupterassembly.

The operating mechanism of the interrupter switch iassembly 8 may bemost easily understood by observing FIG. 1l which shows it in closedcircuit position. The operating linkage consists in the earlieridentified lever 76 carrying a roller 74 lat its end for receiving forcefrom plunger 11 through contact actuating rod 72. Lever 76 actuallyconstitutes a pair of congruent levers, see FIG. 10, but it will bedescribed as a single member that is ladapted to pivot on a fixedtransverse bolt 103, carrying spacer sleeves 104, spanning lbetweenparallel insulating plates 90, 91. There is a single link pivotallyattached to lever 76 by means of a pin 106. Link 105 has `attached nearits lower end a pair of thin guide members 107 that are each providedwith `an elongated slot 108 for the purpose of riding along a fixedguide pin 109. The thin guide members 107 are pivotally connected tosolid link 105 by means of a pin 110 and grooved spacers 111 which haveattached between them one hooked end 112 of a pair of overcenter coilsprings 113. Also pivotally attached to pin is another double memberlever 114 mounted on fixed pivots 115 supported on opposite insulatingplates'90, 91 as shown and secured by any suitable means such as snaprings.

The mechanism thus far described is adapted to transmit force to a pairof movable contact arms 100, 101 journalled on fixed post pivots 116secured to opposite insulating plates 90, 91. Contact `arms 100, 101 mayalso be of an insulating material such as phenol formalde- Movablecontact arms 100, 101 each carry an arcuately shaped switch bladeidentified by the common numeral 117 of copper or similar highlyconductive material provided with tips 118 made of copper-tungsten alloyto prevent their deterioration under the influence ofV an electric arcwhich is generated during the interruption process. Blades 117 areserially connected to each other by means including a transverse rivet119 which extends between them. The arcuate switch blades 117 bearagainst the outside of the opposite movable contact arms 100, 101 andthey are secured further thereto by means of an additional rivet 120.Also secured to each respective movable arm by means of a rivet is apair of roller support brackets 121 which extend in parallelism at anobtuse angle away from the contact arm 100, see FIG. 1l. Another longtransverse rivet 122 provided with insulating spacers, not shown,

carries the pair of brackets 121. A roller 124 is sup- -ported on anaxle pin 125 that spans between the two support arms 121. The same pin125 serves as a means .of attaching another hooked end 126 of spring113.

Operation of the interrupting switch may be most easily comprehended byexamining FIGS. l1, l2 and 13 in sespring 113 lies through the centersof pins 110 and 125 .and above the center of the contact arm pivot pin116.

In this case the force generated by spring 113 is such as to create acounterclockwise moment of force on lever 7.6 so that plunger rod 72 isheld upwardly. When solenoid coil 7 is traversed by minimum tripcurrent, plunger 11 descends to an intermediate position as shown inFIG. 12. This position corresponds with that shown in FIG. 5 and itrepresents that the timing interval of that particular stroke has beencompleted. Note in FIG. 12 that coil spring 113 has been fully extendedalthough its line of action still lies above the center of contact armpivot 116 so that the contact arm has not as yet begun to move. Atapproximately this time, however, plunger 11 continues its downwardmovement with an unimpeded quick final portion of its stroke and theactuating rod 72 is about to cause lower roller 124 to be impacted bythe upper roller 74. Impacting of these two rollers occurs as theplunger moves from its position in FIG. 12 to that of FIG. 13 and at thesame time the line of action of spring 113 passes below the center ofpivot 116 so that movable contact arms I100, 101 are jointly rotated toa position where their motion is arrested by collision with heavy masses97, 98. This condition is exempliied in FG. 13 where the interrupter isshown in full open position.

If lockout has not occurred, that is, it plunger 11 is not permanentlyrestrained in the downward position of FIG. 13, spring 113 is able toforce the plunger 11 upwardly to its original position. This occurs as aresult of pin 125, carried in the roller support 121, acting as a fixedpivot point for the overcenter spring 113 and the opposite end 112 ofthe spring exerting a lifting influence on arm 114 and thereby causingits clockwise rotation about pivot 115. 'Ihis rotational moment isconverted to a translatory force in link `105 that causescounterclockwise rotation of lever 76 and the exertion of a linear forceon plunger 11. During closing of the interrupter switch, the line ofaction of spring 113 passes above contact arm pivot 116 by reason of end112 of the spring moving lthrough a clockwise arc. Thus, after theplunger has been restored to its uppermost position, the line of actionof spring 113 is such that it exerts a counterclockwise influence oncontact arms 100, 1011 causing closure of the interrupter switch again.

When contact arms 100, 101 swing clockwise during switch opening to aposition where they are arrested by the masses 97, 98 there is anenormous amount of kinetic energy which must be dissipated lest thecontact arms rebound and cause restriking of the arc drawn on the 'tips118 of arcuate or sickle shaped blades 117. A novel and simple way ofcoping with this problem is here presented. It was discovered that ifthe dynamic parameters of the colliding movable and stationary elementscould be properly coordinated that rebound of the movable contact armcould be minimized if not entirely eliminated. By coordinating thedynamic parameters of the elements is meant that due regard is paid totheir kinetic energy expressed in terms of their masses and velocitiesas well as the materials out of which they are made. Now it is wellknown in the art how to damp the movement of a rapidly traveling elementby applying Various force absorbing devices at a proper time, but in theinstant case it was discovered that rebound of the movable contact armarrived at a minimum between two maxima when a certain critical mass wasadopted vfor the cylindrical members 96, 97 and 93 which `form the stopsfor arresting movement of the contact arm. As a practical matter,therefore, contact rebound can be minimized surprisingly easily and withvery little experimentation to determine the critical mass of thearresting stops. In the instant case cylinders `of different outsidediameter were substituted until a point was reached Where damping wasfound to be optimum.

It is diicult, if not impossible, to set forth specific dimensions orcharacteristics of an anti-rebound arrester applicable to all cases of acircuit interrupter design. But by way of example, in accordance withthe present invention, steel cylinders 97, 98 were used although it ispossible to use brass or other metal of other than round cross section.In order to apprise those practicing the art of the considerationsinvolved so as to facilitate application of the principle to otherpractical cases, it may be stated that the substance out of which thespaced insulating plates is made should be yieldable in nature andpossess a low coefficient of restitution. That is, it should be asubstance such as phenol formaldehyde resin that absorbs a large amountof impact energy by converting the same into heat while it is deformingslightly and which likewise develops further heat by intermolecularfriction when the substance is restoring itself to its original positionas a result of its inherent resiliency. The metal comprising the stopsmay be such that it is perfectly elastic but subject to only a smalldeformation when impacted. In other words, it is rather important thatthe lstops be of hard material and of such magnitude that the mass willtranslate and cause deformation of the supporting plates as describedearlier. if the mass is excessively great no translation of it willoccur and the contact arm will rebound sharply, because the mass willnot translate sufficiently to compress the supporting material and yieldenergy thereto as described above. It the mass is stoo small, it willtend to translate at undiminished velocity and therefore recoil sharply.The optimum condition is that where the mass is of such value that itaccelerates in the same direction as the contact arm moves after impactoccurs and thereby absorbs some of the kinetic energy of the movablecontact by exchange of momentum while storing energy in the supportingmaterial. The supporting material must yield its stored energy towardaccelerating the mass in the opposite direction at such rate that themass and movable contact arm remains in contact all during. theinterval.

It should be appreciated that were it not or space requirements dampingcould be further augmented by alternately stacking metal masses ofcritical proportions with masses of laminar semi-compressible material.In the instant case this arrangement is approximated by alternate metalto phenolic layers where metal blades 117 are carried on phenolic armssuch as which in turn impact metallic critical masses 97, 9S carrieddirectly on phenolic plates 90, 91. Y

The arc extinguishing structure of the novel interrupter is a fluidimmersed type especially adapted to cooperate with arcuate movablecontact blades 117. Reerring to FIG. 14, it will be seen that the arcextinguishing structure comprises a pressure generating chamber and anexhaust chamber 131 connected by means of a cross blast tube 132 of ber`or similar material. Each chamber 130 and 131 is provided with a wall133 and 134, respectively, in compressive relation with opposite ends ofthe cross blast tube 132. The respective walls are apertured at 135 and136 for the purpose of placing the pressure generating chamber andexhaust chamber in communication.

Each chamber is composed of a plurality of stacked discs 137 having asubstantially circular central portion for dening an arcing cavity 138and a rectangular slot 139 'which when congruently stacked forms thecavity housing a stationary contact element designated generally by thereference numeral 140. One end of the pressure generating chamber 130 isclosed by means of a relatively thick insulating wall 141 which issubstantially imperforate except for a small hole 142 that allows reiillof dielectric fluid into the arcing chamber 138 after interruption hasoccurred.

The outside wall of the exhaust chamber 131, see FIG. 14, is providedwith a plurality of small holes 143 for the purpose of discharging thegaseous arc products into the ambient dielectric fluid.

The stacks of apertured discs 137 may be tightly compressed betweentheir walls 133 and 141, for example, to for-m an individual chamber 130held together by means such as rivets 144. The chambers 130 and 131 areheld in compressive relation to the ends of cross blast tube 132 bymeans of through bolts 145 provided with suitable spacers 146 betweenand on opposite sides of parallel insulating plates 90, 91. Theindividual charnbers are further secured to the insulating plates byadditional stud bolts 147 provided with insulating sleeves. It will beseen that the chambers 130 and 131 and the cross blast tube 132 form anintegral unit with plates 90, 91 so that the whole interrupter switchassembly 8 may be attached to the lower side of the solenoid coilassembly and held only by a pair of nuts 94.

The stationary contact assemblies 140 in each of the chambers 130 and131 are substantially identical. They comprise a pair of complementaryfingers 149 having arcing tips 150 at one end and a right angle offsetbend 151 at the other end. Fingers 149 are compressed toward each otherby compression springs 152 carried on a pin 153 which extends looselythrough each of the fingers. Springs 152 may be retained on the pin byany suitable means such as snap rings or washers, for example. Fingers149 are further guided, held in alignment with each other, and limitedin inward movement by a double shoulder pin 154.

The oset portions 151 of fingers 149 are adapted to act as a fulcrumpoint when the fingers are spread by admission of the tips 118 ofarcuate shaped movable contact blade 117. Fingers 149 are held incompressive current interchange relation with a stud terminal post 155by means of the compression springs 152. The terminal post is threadedat its upper end for receiving an appropriate lead wire, not shown. Inorder to eliminate pitting between the offset portion 151 and stud post1575, an auxiliary current path is provided from the fingers to ametallic terminal block 156 supporting the stud post through the agencyof thin shunt strips 157. Electrical connection between the shunt strips157 and the terminal block 156 'is effected by compression through themedium of rivets 144, see FIG. 14. The terminal block 156 has a topportion in which stud post 155 is threaded and a back portion whichcloses the arcing cavities 138 and prevents discharge of gases therefromduring the arcing process.

At least one of the fiber discs 137 is provided with a radial hole orslot S for the purpose of admitting the arcuate movable contact blade117. The tips 150 of the stationary contact fingers 149 extend into thecircular portion of the discs 137 so that engagement with the movableblade tips 118 may be effected. The location of the stationary fingertips 150 is substantially diametrically opposite from the contactadmitting holes 158.

As explained earlier, the arcuate blades 117 are carried on individualmovable contact arms 160, 101 and the blades are serially connected toeach other at least `by means such as a rivet 119. Thus, when theinterrupting switch is closed, there is formed a series circuitoriginating at one of the terminal studs 155, passing through each ofthe stationary contacts 140 and the movable blade 117 and terminating atthe opposite stud 155.

Arcuate blades 117 may be of substantially the same lengths so that whenmovable contact arms 100, 101 are swung jointly in a clockwisedirection, see FIGS.. 12 and 13, while the unit is conducting, arcs aresimultaneously drawn in the pressure and exhaust chambers 130 and 131.Under this circumstance the gases incident to arcing in the pressurechamber 130 are expelled through cross blast tube 132 and into theexhaust chamber 131. Gas is also generated in the exhaust chamber but itis fully relieved through the plurality of small holes 143 and it isfurthermore swept out by the high velocity gases pro- 'jected across theexhaust chamber arc from the cross blast tube 132. After the arc isextinguished and the intervrupter switch is in its full open position asin FIG. 13,

dielectric fluid is replaced in the arcing structure by ingress throughholes 142, 143 and 159, for example.

It was indicated earlier that the recloser executes a number of ltheopening operations followed by a number of closing operations, and thatif the fault is permanent, the recloser locks out. The mechanism forcausing lockout Vof the interrupter by causing plunger 11 to descendpermanently for the purpose of opening up the interrupter switchcontacts is generally indicated by the toggle link mechanism identifiedby the reference numeral 26 in FIG. l. A more detailed description ofthe lockout mechanism may be found in the above-cited Van Ryan patent,but for the present purpose it is sufficient to appreciate that lockoutoccurs whenever trip finger 25 is struck by integrating piston extensionstern 15 and the -the trip finger 25 is struck to cause lockout.

toggle link assembly 26 breaks. Attention is now invited to the novelintegrating piston assembly and its related parts which are soconstructed as to enable convenient selection of the total number ofinterrupter operations prior to lockout and the independent selection ofthe total number of fast operations which precede 'the slow or retardedoperations. Integrating piston 13, see FIG. 3, is adapted to advance insteps toward escape orifice 45 each time the interrupter operates.Likewise, when the integrating piston 13 is elevated to its ultimateposition, trip piston extension stem 15 is also raised toward proximitywith trip finger 25. When the trip finger 25 is struck by extension 15,the toggle link mechanism breaks causing lockout, after which theintegrating piston 13 is free to resettle to its lowermost positionwherein it resides in FIG, 3. After manually resetting the interrupteras described in the Van Ryan patent, integrating piston 13 will haveresettled and prepared itself for repeating its full number ofoperations prior to lockout.

Note that the integrating piston is provided with an integral extensionneck portion to which is attached a sleeve-like coupling member 166provided with an annular shoulder 167 bearing against a stop 168.Coupling sleeve 166 is attached to piston neck 165 by means of aremovable pin 169 adapted to reside in any one of a plurality of axiallyspaced holes 170 in the lower diametrically reduced portion 171 of thecoupling. In FIG. 3, it will be observed that pin 169 resides'in thelowermost of the holes 170 so that integrating piston restssubstantially at the bottom of cylinder 14. With this adjustment,integrating piston 13 is required to advance several steps before itblocks escape orifice 45 and corresponds to adjusting the interrupterfor executing a like number of fast operations followed by a number ofretarded operations established by means to be explained shortlyhereinafter.

Comparing FIG. 3 with FIG. 8 it will be seen that the latter figureshows the integrating piston 13 advanced axially upward into coupling166 by causing pin 169 to be set in the uppermost of the series of threeholes 170 in the restricted portion 171 of the coupling member. Thus,

vin FIG. 8 integrating piston 13 is elevated to a position where onlyone fast operation of the interrupter will advance the piston to aposition where it blocks escape orifice 45 after which there will be aselected number of retarded operations. From the construction justdescribed it is seen that selection of the number of fast and retardedvoperations is made very convenient in contrast to the prior artprocedure of substituting an integrating piston w1th greater or lessaxial height, but preferably of the same weight, in order to establishits initial position with respect to the escape orifice.

Stop 168 which supports coupling 166 and accordingly establishes theoriginal height .of integrating piston 13 also permits the coupling todepart from said stop in an axial direction in accordance with movementof the piston. It is readily apparent that the initial axial distancefrom shoulder 167 of the coupling to the upper end of the trip pistonextension stem 15 is a determining factor as to how many steps theintegrating piston must take before This choice can also be convenientlymade in the field through the provision of a split pin 1'73 which allowsadjustment of trip piston extension stem 15 axially of the coupling 166.To facilitate this adjustment, stem 15 has a portion 174 of reduceddiameter arranged for telescoping inside the bore of coupling 166 and aplurality of axially spaced holes 175 are also provided for receivingthe cotter pin in its various positions.

When the extension stem 15 is positioned as in FIG. 3, the interrupteris set to execute four operations prior to lockout, that is, fouroperations occur before the upper end of extension stem 15 strikes tripfinger 25 for releasing lockout mechanism 26. In FIG. 8 it is seen thatstem 15 is advanced upwardly one hole so that there will be only threeoperations prior to lockout. This is also a great convenience since itenables a customer to choose any number of operations to lockout inorder to obtain proper coordination with other reclosers in the powersystem without being required to Vfollow the prior art practice ofstocking interchangeable integrating piston assemblies for accomplishingthe same purpose.

Thus, it Iis seen that there has been described in considerable detail arecloser that facilitates discretionary selection of its operationalsequence, and inherently times each operation with precision so thatcircuit interruption will be effected through the agency of a novelinterrupting switch means at the most appropriate time to the end thatcoordination and usefulness of the device will be enhanced.

Although only a preferred embodiment of the inven tion has beenillustrated and described the disclosure is not to be interpreted aslimiting, for the invention may be variously embodied and is to beconstrued in accord with the claim which follows.

It is claimed:

An arc extinguishing device of the liquid immersed type, comprising aninsulating cross blast tube, a pressure generating chamber and anexhaust chamber each having one end wall aperture in substantialregistry with the bore of the tube, said pressure chamber having anothersubstantially imperforate end wall and said exhaust chamber having anend wall provided with a plurality of exhaust perforations, said lastnamed end walls being opposite from the said apertured wallsrespectively, the portions of said chambers between said end wallscomprising a plurality of substantially identical stacked aperturedinsulating discs whose axes are in substantial parallelism with saidtube, elongated tension means holding said tube and the insulating discsof said pressure generating and exhaust chambers in axial compressionagainst the axial blast forces generated when arcing occurs, at leastone of the discs in each chamber being discontinuous for dening aContact admitting hole directed radially with respect to the axis of thetube, stationary contact means disposed interiorly of each chamber andsubstantially opposite said radial holes, contact arm means pivotallymounted for swinging movement about an axis parallel to the axis of saidtube and displaced therefrom, a pair of movable contact blades carriedon the arm means and each having a curvature whose center is incoincidence with the pivotal axis of said Contact arm means and whichintersects said stationary Contact means and said radial hole, so thatsaid movable Contact blades will move closely through said radial holesand into and out of engagement with the stationary contact means uponswinging movement of said Contact arm means, the movable contact bladein said exhaust chamber being spaced from said perforate wall so thatoil and ionized gases may exhaust from said opening regardless of theposition yof said blades.

References Cited in the le of this patent UNITED STATES PATENTS1,934,454 Spurgeon Nov. 7, 1933 2,627,566 Leeds Feb. 3, 1953 2,647,973Umphrey Aug. 4, 1953 2,692,925 Schindler Oct. 26, 1954 2,734,972 VanRyan et al Feb. 14, 1956 FOREIGN PATENTS 413,751 Great Britain July 26,1934 479,850 Great Britain Feb. 11, 1938

